Fuel injectors, particularly those which are suitable for use in gas turbine engines, are required to operate efficiently over a wide range of conditions while at the same time producing minimal amounts of noxious emissions, particularly those of the oxide of nitrogen. This, unfortunately, presents certain problems in the design of a suitable fuel injector. Thus the characteristics of a given fuel injector under light up and low speed conditions are different to those under full power conditions. Consequently a fuel injector is often a compromise between two designs so that it is able to operate under both of these conditions. This can result in a fuel injector which produces undesirably large amounts of the oxides of nitrogen, at least when it is operating under one set of conditions.